Numerical analysis of the swirl intensity decay rate for internal turbulent swirling flow

In this research the trend of swirl decay and factors influencing the turbulent swirl flows have been investigated in a fixed pipe. In this regard, turbulent swirling decay flow with solid body rotation has been numerically surveyed using different flow conditions at the pipe inlet. The numerical results have been validated and compared with the existing mathematical relations having satisfactory agreement. Results show that the swirl intensity decay rate has strong dependency on the Reynolds number. On this basis, correlations have been proposed which improves predictions of swirl intensity decay rate at upstream regions and those with high swirl intensity. In addition, analyses have been made to demonstrate that the previously developed correlations for predicting swirl intensity decay rate, agree with those provided in this study only for regions far enough down stream having the low swirl intensity. This implies that the swirl intensity decay rate should be a function of the type of swirl generator at the inlet.